What 210 × 297 mm means
A4 gives a full writing sheet for dense daily, project and notes pages. The finished rectangle does not define a punch pattern, printer margin, cover or binding fit.
The builder preserves these finished dimensions and will not silently scale the page to make an incompatible imposition fit.
Choose a source sheet and binding clearance
Print directly on A4. A4 cannot be centered at 100% on US Letter because its 297 mm height exceeds Letter’s 279.4 mm height, and neither A4 nor Letter can hold two A4 pages side by side at 100%. Choose direct A4 rather than allowing a print dialog to shrink the page.
Centered and two-up files include crop marks where there is room outside the finished page. A mark is omitted where a source-sheet edge is already the finished edge; this does not change the page dimensions.
The inner content margin moves writing areas away from the selected binding edge. It is content clearance, not a punch-hole coordinate or a promise that a particular punch will fit. Trim first, then align the finished sheet with the punch maker’s physical guide.
Run one measured test
Download a one-page test before committing to a full run. In the print dialog, choose the paper named in your plan, turn off Fit or other scaling, and measure the calibration mark. A mathematically correct PDF cannot predict a printer driver, printable area, feed path, or borderless setting.
After trimming, measure width and height before punching. If the result is off, correct print scaling or the selected source sheet; do not compensate by guessing new page dimensions.